package homework.My21Point;

import java.util.Scanner;

public class magicNubser {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);



        while (scanner.hasNextDouble()){
            double v = scanner.nextDouble();
            if (v > 90) {
                System.out.println("a");

            }
            if (70<v&&90>v){
                System.out.println("b");
            }
            if (60<v&&70>v){
                System.out.println("c");
            }
            if (60>v){
                System.out.println("不及格");
            }
        }
    }
}
